A Structured Cu-Based/γ-Al<sub>2</sub>O<sub>3</sub>/Al Multifunctional Catalyst for Steam Reforming of Dimethyl Ether: Investigation on in-Situ CO Reduction Strategy

Ni/MgO−Al 2 O 3 multifunctional catalysts were synthesized and applied to toluene reforming with a microchannel reactor to obtain hydrogen-rich syngas and lowest deactivation by carbon deposition. These catalysts were characterized by inductively coupled plasma-atomic emission spectroscopy, N 2 adsorption−desorption, X-ray diffraction, H 2temperature programmed reduction, NH 3 -temperature programmed desorption, and transmission electron microscope-energydispersive spectrometer. The results showed that MgO−Al 2 O 3 support had the largest Brunauer−Emmett−Teller surface area and formed a steady MgAl 2 O 4 spinel structure after 800 °C calcination, which is conducive to preventing Ni sintering, increasing Ni dispersion, and thus improving catalytic activity. Less than 15% Ni loading maintains a high dispersion on the MgO−Al 2 O 3 support, but 20% Ni loading caused a sharp decline in the surface area and dispersion effect, which is due to Ni sintering and pore plugging. Meanwhile, 15% Ni/MgO−Al 2 O 3 shows a higher catalytic activity and excellent stability than others. In addition, the microchannel structure increased the surface area-to-volume ratio and enhanced the heat-transfer coefficient, hence had a prominently promotive effect on the catalysts utilization efficiency.

Section: Introductionmentioning

confidence: 99%

Hydrogen-Rich Syngas Production by Toluene Reforming in a Microchannel Reactor Coated with Ni/MgO–Al₂O₃ Multifunctional Catalysts

Jiao

Zhang

et al. 2019

“…Under such a condition, the Cu species are prone to migration and sintering, which leads to deactivation of the catalysts. − Thus, it is a great challenge to achieve efficient catalysts with ultra-high Cu dispersion at high reaction temperatures. Moreover, a small amount of CO can poison the Pt electrode of the hydrogen fuel cell, so the side reactions of methanol direct decomposition and reverse water gas shift (r-WGS) need to be effectively inhibited to suppress CO production. − …”

Section: Introductionmentioning

confidence: 99%

Sputtered Cu-ZnO/γ-Al₂O₃ Bifunctional Catalyst with Ultra-Low Cu Content Boosting Dimethyl Ether Steam Reforming and Inhibiting Side Reactions

Sun

Tian

Zhang

et al. 2019

Dimethyl ether steam reforming (DME SR) is one of attractive technologies to online provide H 2 for fuel cells in vehicles. Herein, we adopt a novel sputtering method to prepare a Cu-ZnO/γ-Al 2 O 3 (CuZn− S) bifunctional catalyst with only 2.9 wt % Cu loading. The interaction between Cu and ZnO suppresses the thermal aggregation of Cu nanoparticles in DME SR. The Cu nanoparticles (methanol steam reforming sites) are highly and homogeneously dispersed and anchored on the external surface of γ-Al 2 O 3 (DME hydrolysis sites). It significantly improves the utilization efficiency of the Cu species and the mass transfer, thereby achieving high catalytic performance for DME SR. Its reaction rate per unit mass of Cu is 50 times to that of the CuZnAlO/γ-Al 2 O 3 catalyst at 300 °C. In addition, this unique structure inhibits the side reactions of methanol direct decomposition and reverse water gas shift to suppress CO production.

“…However, high temperatures (>300 °C) are generally needed for DME hydrolysis over γ-Al 2 O 3 . Cu-based catalyst is commonly used in MSR (eq 3 ) because of its low cost and high activity, whereas it has low thermal stability and poor catalytic performance, since copper species are gradually aggregated at temperatures above 300 °C. − Then, the component Ni was found to be effective for suppressing copper sintering and enhanced stability of Cu-based catalysts dramatically . Nevertheless, the nickel-modified Cu-based catalysts showed high byproduct yields with ca.…”

Section: Introductionmentioning

confidence: 99%

Insights into the CO Formation Mechanism during Steam Reforming of Dimethyl Ether over NiO/Cu-Based Catalyst

Fan

Zhao

Hou

et al. 2019

Self Cite

Steam reforming of dimethyl ether on Cu-based catalyst was experimentally studied. It is found that formation of H2 and CO2 occurred over Cu/γ-Al2O3/Al, while methanol decomposition to CO and H2 was the main reaction over Cu/Ni/γ-Al2O3/Al in methanol steam reforming (MSR), which is similar to that on metallic Ni. However, XPS results show that nickel species existed as an oxidation state (NiO) over Cu/Ni/γ-Al2O3/Al. Therefore, reaction pathways of MSR over Cu(111) and NiO/Cu(111) were further explored using theoretical density functional theory calculations, and it was found that different reactivities of CH2O* resulted in the distinct product selectivity. On Cu(111), CH2O* reacting with OH* to CH2OOH* is favored, while CH2O* prefers to dehydrogenate to H* and CO* directly on NiO/Cu(111). This provided further evidence on the experimental results and fundamental understanding on the role of NiO species in affecting the MSR mechanism, which was helpful for rational design of selective Cu-based catalysts.